Date of Award

12-2007

Level of Access Assigned by Author

Campus-Only Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Wildlife Ecology and Wildlife Conservation

Advisor

Malcolm L. Hunter Jr.

Second Committee Member

Phillip deMaynadier

Third Committee Member

Daniel J. Harrison

Abstract

The conservation of some rare and endangered turtles is complicated by their far-ranging movements and diverse habitat requirements. Semi-aquatic turtles often use a variety of widely scattered wetlands to fulfill seasonally-dynamic needs, thus frequently undertaking terrestrial movements that expose them to multiple threats. Habitat conservation and management to mitigate threats requires understanding habitat relationships and accounting for both spatial and temporal shifts in habitats occupied. Using radio telemetry, I investigated the dynamics of seasonal wetland use by spotted turtles (Clemmys guttata) and Blanding’s turtles (Emydoidea blandingii) in Maine, along three axes of hypothesized habitat requirements: thermoregulation, food, and cover. Seasonal use patterns were then examined in a temporally-segregated manner, pooling and comparing wetlands used during one period with those used during other activity periods. Distinct seasonal movement patterns were detected in both species and a logistic regression approach revealed significant differences in characteristics of wetlands across seasons for both species. Spotted turtles exhibited a positive association with wetlands hosting abundant wood frog (Rana sylvatica) egg masses in spring and little use of mostly forested wetlands from spring through late summer. Wetland use by Blanding’s turtles’ suggests seasonally-dynamic needs for spring and early summer thermoregulation (deciduous-dominated wetlands with high sun exposure), early summer food (wood frog egg masses), and spring and fall cover (sphagnum, emergent vegetation, and deep water). I conclude that a comprehensive approach toward habitat conservation for these rare and declining turtle species needs to be informed by an understanding of their complex seasonal movement and habitat use patterns.

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